1. Field of the Invention
This invention relates to a new process for the production of a 4-aminobutyric acid or its derivatives from a 3-carboxamido-propionic acid or its derivative. More particularly, this invention relates to a new chemical process of producing 4-aminobutyric acid or its derivatives by utilizing a novel chemical reaction which has now been discovered by the present inventors during their researches of the chemical conversion of a primary carboxamido group into nitrile group.
Heretofore, various processes of converting a primary carboxamido group ##STR1## into a nitrile group were known, including the method of treating the carboxamido group with dicyclohexylcarbodi-imide (B. Liberek et al., "Tetrahedron" 22, 2303 (1966)); the method of treating the carboxamido group with thionyl chloride (C. Ressler et al., "Journal of Organic Chemistry" 36, 3960 (1971)); the method of treating the carboxamido group with tosyl chloride (M. Zaoral et al., "Coll. Czech. Chem. Comm." 24, 1993 (1952)); and the method of treating the carboxamido group with trifluoroacetic acid anhydride (F. Campagna et al., "Tetrahedron Letters" No. 21, 1813 (1977)). However, all of these prior art methods suffer from many disadvantages in that the reagents employed therein are expensive, in that the reaction conditions for the conversion are severe and vigorous, and/or in that there is a need to use such a protected derivative of the starting compound of which the carboxyl group and/or amino group has or have been protected by suitable protective groups, in order to prevent any undesired side-reaction during the conversion.